However, it emerged that using the amount of energy needed to kill Klaus would also kill her.

Speaking to TV Guide, Graham explained that Bonnie will start to work out a plan in tonight's instalment.

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"Bonnie is on her journey to how she's going to take out Klaus," she said. "She will do what she has to do to protect Elena."

Graham admitted that Bonnie is terrified about the situation, saying: "Bonnie is filled with fear. She's still only a 17-year-old girl and scared, but is able to move forward and face her fears. That's where her head is at - she can be scared out of her mind, but she presses forward and will do what she has to do."

She added: "A lot changes in the episode [and] Bonnie puts a lot on the line. I think if Bonnie ever went down, she'd go down with a fight."

The Vampire Diaries airs on Thursdays at 8/7c on The CW in the US and on Tuesdays at 9pm on ITV2 in the UK.